OK. Here we go. This is one of my favorite subjects.

As a former Scuba Instructor (Naui/Padi) I have an opinion, and as a 6 foot four, 225 lb. waterman raised on So Cal Beaches, I have another.
Here is what decided it for me.

I was bored at the dive shop one day, and saw the "swimming belt" we had lying on the pool deck.
This belt was made of stout surgical tubing, and was tied to the hand rail in the deep end of the pool.
The other end was tied to a weight belt, without weights. The tubing was long enough to stretch from the rail to ALMOST the farthest corner of the pool.
Get it?
We could swim non-stop and not touch the corner. We also didn't have to do flip turns in our small POS pool. ( POS = not very good.)
I took every type of fin we had from our sales shelf and tried it in our pool.
Don't forget, I am a monster in the water.
Some fins got me just so far; others fell off my feet! Repeatedly!
My UDT's stayed on and got ME the furthest. Period.
That is the fin I used, and my safety divers used.

Of course I was trained by a former Navy SEAL, and that is what he used. I just wanted to see for myself.
Later on as a Marine in BRC, that is what we would use as well.

There is no substitute for a stout fin and strong leg muscles.

For me, there is no second choice.